Minimal pulsation a must for transferring viscous suppository mass

The manufacture of suppositories requires a steady transfer of viscous mass in a low pulsation environment.

The slightest fluctuation in temperature, or pressure, can cause the mass to harden, affecting the quality of the final product.

Dr. Pfleger Arzneimittel is behind numerous prescription medicines in urology, dermatology and pain-relief as well as many recognised over the counter brands such as Bio-H-Tin, Ipalat, Neuralgin and Mykosert. In its ultra-modern production facility in Bamberg, the company also manufactures the products of many pharmaceutical companies, and offers comprehensive services from product development, manufacturing and packaging through to distribution. In addition to tablets, film-coated tablets, capsules, ointments and creams, Dr. Pfleger Arzneimittel also manufactures and packages suppositories.

Precise control required

During the manufacture of suppositories, only a small amount of the product is moulded into the cavities at the filling stage. The remaining product is pumped back into the preparation tank to repeat the process. Given the repetitive nature of the process it is particularly important that the temperature is kept constant between 35-38 degrees celcius.

"At just two degrees below this value, the mass would harden and settle, and the entire production process could come to a standstill." said Martin Schaller, Technical Services Project Manager at Dr. Pfleger Arzneimittel. The homogeneity of the suppository mass, and thus the even distribution of the active ingredient, could also be affected.

Initially, a rotary lobe pump was used to recirculate the suppository mass during production. “Not only did the rotary lobe pump have an annoyingly high noise level, but over time its maintenance costs also increased," reports Martin Schaller. Recurring leakages led the team at Dr. Pfleger Arzneimittel to look for a more dependable alternative.

Reliable and pulsation-free

The innovative sinusoidal pump design offers high levels of reliability as well as low cleaning and maintenance costs. Virtually pulsation-free pumping means the Certa pump ensures maximum accuracy when dispensing the suppository mass. The Certa Sine pump from MasoSine, part of Watson-Marlow Fluid Technology Group, was selected for this purpose.

To avoid the suppository mass hardening the process pump had to deliver a stable and reliable flow. The pump also had to be capable of handling viscosities of approximately 4,000 to 6,000cP, and meet the sanitary standards demanded of the industry.

"Of upmost important is that the pump transfers constantly and without pulsation peaks," says Mr Schaller. High pressure peaks in the volumetric dosing pumps at the filling station could lead to problems with the dosing accuracy. In extreme cases, the uniformity of the suppositories and thus the product quality would suffer.

Easy cleaning and aseptic assurance

Designed with only one rotor, one shaft and one seal, the number of parts in contact with the product is reduced to a minimum. Disassembly and cleaning are therefore much easier and quicker. In addition, this design offers significantly lower energy consumption than comparable positive displacement pumps. The Certa pump also offers extensive EHEDG EL Class I Aseptic and 3A certification and can be used in aseptic processes as it is bacteria-proof and requires no additional steam connections.

"Compared to our previous rotary lobe pump, the mechanical seal of the sine pump is much easier to access. Unlike the rotary lobe pump, manual cleaning of the mechanical seal can be done with minimal effort. In addition, the static flushing of the seal is much easier to carry out and the seal is also easier to control visually," said Mr Schaller.

“Pump and product are a perfect match”

During comprehensive preliminary tests over a period of nine months, not a single pump failure occurred. “The Certa pump has been working completely smoothly in the production line to date. The pump has no problems whatsoever handling the viscosity. Plus, the relative ease of disassembly has led to time savings for cleaning and maintenance work", confirms Mr Schaller. Furthermore, the use of the sine pump has led to a significant reduction in the noise level in the preparation area. Most importantly, thanks to the virtually pulsation-free pumping of the viscous mass, the dosing pumps at the filling station work precisely and the suppositories are one hundred percent uniform.